Copper Talk » Ask The Tech » Antennas » Effects of high altitude on full wave length antenna rule « Previous Next »

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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 362
Registered: 7-2004


Posted on Tuesday, September 14, 2004 - 11:14 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech833 I hope you don't mind but I was told to ask you about this.

This has been bothering me for a while, and has become pretty confusing with the info I've received up to this point, so here goes.

I think there might be some advantages to living at 7800 feet with a clear shot across the High Desert all the way to the continental divide.
I don't know again that’s why I'm asking. But it seems logical that at 7800 feet or so on the east facing up slope of a 9,952-foot mountain. I would be at least partially exempt from the full wavelength rule.

Right now I have the antenna on a tri-pod on top of the house placing it at 30 feet to the feed point. If it would make a real difference I could hire someone to climb up and add another 4.5-foot section of mast pipe to my existing 10 foot section to get it to 34.5 feet to the feed point.

This is what throws me. With my Yasue FT2800m and a Diamond CP22-E antenna at 20 feet to the feed point running 65 watts. I can regularly hit 2-meter repeaters in Las Vegas, which is 220 miles away, and Kingman, Arizona. 280 miles away with good results (using map quest to determine the distances) and when ground conditions are really good I've keyed the Flagstaff repeater 470 miles away. Since I don't hear about people hitting repeaters on a regular basis 200 miles and further away. I would think that this is a result of living at this altitude.

I would also think this advantage would show on 11 meters too and possibly allow me a little leniency on the full wave length rule. I could be wrong, and would really like to know if I am. And if I am wrong is the extra 4.5-foot section of mast pipe going to make a real difference in DX or ground wave contacts?

Thank you very much in advance

Bob
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 375
Registered: 7-2004


Posted on Wednesday, September 15, 2004 - 10:23 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Ok maybe I shouldn't have posted this for Tech833 alone.

I have been questioning my antenna height since the other day when I was told I needed to get my I-Max 2k to 36 feet. I just have to wonder how much difference the added 6 feet would make. I can add a 5-foot section of mast pipe taking it from 30 feet to 34.5 feet, but is it really going to make a perceptible difference?

Any advice would be appreciated
Thanks in advance
Bob
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Tech808
Moderator
Username: Tech808

Post Number: 3594
Registered: 8-2002


Posted on Wednesday, September 15, 2004 - 10:41 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Yes you will Notice a Difference.

Get it as Close to 36' as you can or that is possible.

If you are Under 36' to the Bottom Load of the IMAX, Tech833 Recommends using the GP Kit.

He spent a lot of time testing it and writing his Review on it for the Copper Forum Members and he gives you the Best Advice a person can get to achieve 100% Maximum Performance from it.

If it is 34.5 add the GP Kit if it is 35' add the GP Kit,if it is 35.5 add the GP Kit.

His Antenna Farm and his testing of antennas and his advice & knowledge of antennas is the most Accurate there is anywhere.

Take his advice that he posted in his Review and you won't be sorry.

Lon
Tech808
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Tech833
Junior Member
Username: Tech833

Post Number: 45
Registered: 12-2001
Posted on Thursday, September 16, 2004 - 7:59 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Sorry to do this Lon, I disagree.

Altitude gives you two things on HF.

1- Line of sight coverage. If you can see them, you can talk to them.
2- Lower takeoff angle. This will halp your signal stay on Earth and out of space where it is wasted.

Assuming the terrain slopes downward all around your house, adding 6 more feet of mast will do nothing at all. Assuming the ground is pretty flat around your house, it will help, but BARELY.

If you want to make a marked improvement on HF (CB), add a lot of ground wires around your house extending away from the foundation. Then, bond all the wires with a copper strap around the foundation of the house. Then, connect the counterpoise system to your antenna in at least 2 points (two opposite corners of the house). 4 points would be better.

Then, watch your signal really go, and watch your receiver noise drop to nearly zero.

Oh, being in the high desert, don't forget to add a Polyphaser inline. It will actually reduce your receiver noise too by isolating the coax center conductor from the dry wind static you guys get over there.
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Tech808
Moderator
Username: Tech808

Post Number: 3604
Registered: 8-2002


Posted on Thursday, September 16, 2004 - 8:28 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech833,

No Problem, thats is why I ask you about all my antenna questions so I can get it right the first time.

It sure save's me a lot of time and work by following your advice.

Lon
Tech808
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 382
Registered: 7-2004


Posted on Thursday, September 16, 2004 - 9:23 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech833 thank you very much. The house is on an up slope so the front and back are somewhat level with the front sloping down, and when about 150 feet away in that direction is a 30 foot slope down. To the left of the house it is a steady slope going down at about a 15 degree angle for about a mile.

I'm actually in the Forrest above the Desert but because the desert is right below us there isn't much in the way of humidity. So the Polyphaser sounds like a great idea.

I live between 300 and 800 feet from Big Bear valleys floor. The white spot is about the right area, but I'm up higher to the left at least a couple hundred feet higher than the white spot.

the picture on the right shows the desert floor about 3000 feet below

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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 383
Registered: 7-2004


Posted on Thursday, September 16, 2004 - 9:25 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

By the way where do I get a Polyphaser?

Thank you very much for your time and help

73
Bob
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 387
Registered: 7-2004


Posted on Friday, September 17, 2004 - 2:38 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Found the Polyphaser

Thanks again
Bob
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Tech808
Moderator
Username: Tech808

Post Number: 3608
Registered: 8-2002


Posted on Friday, September 17, 2004 - 6:23 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Bob p,

Sorry I did not get to your post sooner.

PolyPhaser 2 KW Model:

http://www.copperelectronics.com/cgi-bin/checkitout/checkitout.cgi?catalogSTORE:CKIE:prodH00-00002+

PolyPhaser 3 KW Model:

http://www.copperelectronics.com/cgi-bin/checkitout/checkitout.cgi?catalogSTORE:CKIE:prodH00-00004+

Lon
Tech808
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 388
Registered: 7-2004


Posted on Friday, September 17, 2004 - 12:16 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Thanks Lon the grounding system Tech833 is talking about sounds great but expensive. I do have allot of white noise, and I know the GPK is supposed to help with that, and now the Polyphaser. But after just spending well over $1000 on the new system any addtional money might be putting my life in jeapordy with Rachael. I might get away with the Polyphaser or the GPK, but not both.
Thanks agian and 73
Bob
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 394
Registered: 7-2004


Posted on Saturday, September 18, 2004 - 2:13 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

this where I live


This is a better shot of where I live. For perspective the green area shown is over a mile from the white spot indicating about where I live. My house is at least 500 feet above the valley floor on the upslope of Sugarloaf mountain.


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Tech548
Moderator
Username: Tech548

Post Number: 296
Registered: 5-2004


Posted on Saturday, September 18, 2004 - 2:46 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Bob

Get your antenna as feasably high as possible. Use the Polyphaser as Tech833 suggested and don't worry about the GPK.

By the way, height has far more to do with ground-wave contacts than it does with working DX. When conditions are right, you can work DX off a tuned coat hanger hanging off your porch.

In other words, there's no trick to working DX. But talking local DX is something we all have to work for. And at your geographical height, I don't really see a problem with this. A lot of guys would love to have a location such as yours.

I believe you have a far better setup than YOU think you do. Quit worrying about it my friend. But if heigth is still a concern to you, save your allowance for a few months and get yourself a 50ft tower.

PS: I'd like to be a fly on the wall when your wife sees that thing go up!

Jeff
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 394
Registered: 7-2004


Posted on Saturday, September 18, 2004 - 6:53 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Thanks Jeff


Rachael would kill me if I bought a tower after finding out how much they go for these days. I was telling her a 40 foot tower would only be a few hundred dollars. Thats what they were 30 years ago, and really didn't expect too much of a change, well thats out.

My main concern in raising the antenna was talking DX, so if raising the antenna isn’t going to make a real difference then I’ll just leave it where it is. I can talk to anyone up here in Big Bear valley that has a radio so that’s no problem. I just thought that it might help me get out a little better when DX is running if I got near that 36-foot mark.

But with what you just said and Tech833 saying that adding another 6 feet even if the house was on level ground at this altitude it really wouldn’t make much difference took away that worry.

What’s funny is my signal goes over the top of the mountain behind me. That’s roughly a steep 2000 feet higher than my location, and I regularly talk to stations 90 and 95 miles away in Lake Elsinore and Temecula Ca. with good results. That’s running the 2970DX at high power on the I-Max 2000. It really surprises me that my signal gets over the top of the mountain to the west of me. I figured that the mountain would block the path west of me completely.

I’m not going to say the furthest I’ve talked on the other side of the mountain, because it sounds ridicules, and it’s only when ground wave conditions are really good so I don’t believe it counts.

As always thanks for responding, I really appreciate your input.

73
Bob
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Tech833
Junior Member
Username: Tech833

Post Number: 46
Registered: 12-2001
Posted on Saturday, September 18, 2004 - 7:55 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Jeff,

Antenna height does have a little something to do with skywave (DX) performance. As you raise the antenna and lower the takeoff angle, your main lobe hits the ionosphere further away, giving you some 'gain' for further skywave. If you prefer close-in skywave, lower your antenna which will raise your takeoff angle and you will get 'gain' for closer DX.

If you ever see pictures of a SW broadcasting station curtain array, you will notice phasing networks designed to change the takeoff angle of the main lobe. We do it on purpose!
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Highlander
Advanced Member
Username: Highlander

Post Number: 612
Registered: 12-2001
Posted on Sunday, September 19, 2004 - 8:08 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Nice pics, btw. Looks like you live in a really beautiful place.
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 395
Registered: 7-2004


Posted on Sunday, September 19, 2004 - 1:11 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

It really is nice here considering we are only a hundered miles or so from L.A. Most of Big Bear Valley is surrounded by high mountains that look beautiful in winter when there's snow caps all around the valley. But here at the south end it's opened east over the High Desert and to the South so it might be better for DX, not as pretty but could be better for radio.
I have to say the summer and late spring months are great. But the winters can be really bad. It's already cooling off and the days are in the 60's and low 70's. Some people live for the winter months, I'm not one of those :-)
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 396
Registered: 7-2004


Posted on Sunday, September 19, 2004 - 1:17 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Oh and by the way the high today is supposed to be 61 degrees.
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Dindin
Intermediate Member
Username: Dindin

Post Number: 386
Registered: 2-2004


Posted on Sunday, September 19, 2004 - 8:39 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

B0b_p,NICE,looks like the spot I use to operate a portable station in early 80's.up on Blue Mountain on the Utah/Colorado border.from there you could see Kings Peak(ele.13,528) which stayed snowcapped year round.
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 398
Registered: 7-2004


Posted on Sunday, September 19, 2004 - 9:09 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Dindin Thanks it really is pretty up here, that picture really doesn't show the valley at it's best .

I think the highest point here is about 12,000 feet and it's not real close to my house.

I guess I was obsessed with getting to that 36 foot mark on the antenna hieght. People kept telling me that I needed to get to the antenna 1 wave length high to get the best performance out of my system, and with the tri-pod and all it would have been pretty hard to get it to that point. So Tech833 was a great help with his answer. It should have been common sense that over looking the desert the way I do a extra few feet wouldn't matter too much.

73
Bob
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 399
Registered: 7-2004


Posted on Monday, September 20, 2004 - 12:15 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech833
I think the entire forum is extremely lucky to have you aboard. You have helped me a number of times and I can't express the gratitude I feel for your assistance. We have other Tech’s and I know they respect your opinion. Tech833 Lon when I asked him the last question I posted about the antenna and altitude suggested that I ask you, and your response was greatly appreciated. He explained the grounding and the counterpoise system you suggested and I will take your advice and attempt this in the early summer after the stacked cords of firewood are out of the way.

Thanks again for your assistance
Bob
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 408
Registered: 7-2004


Posted on Wednesday, September 22, 2004 - 7:01 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech833 By the way after seeing the pictures above is it still your opinion that the addition of an extra 6 foot of mast pipe will do nothing for me? I'm too poor to afford a tower or a beam, and just really want to do the very best I can with what I have. Which is an RCI 2970DX, and I-Max 2000.
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Tech833
Moderator
Username: Tech833

Post Number: 856
Registered: 8-2002
Posted on Wednesday, September 22, 2004 - 11:57 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Bob.

6 more feet will gain you absolutely nothing. More ground conductivity will make a noticeable improvement. Save your money.
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Bob_p
Intermediate Member
Username: Bob_p

Post Number: 410
Registered: 7-2004


Posted on Thursday, September 23, 2004 - 1:40 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech833 I hated bothering you after what you had said, but after I posted the pictures I wanted to be sure nothing had changed.

Like I said I want the best I can do with what I have so as soon as the late spring comes and the ground is clear around the house I will follow your advice.

Thank you very much for your patience and time in answering my redundant questions.
Bob
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Tech833
Moderator
Username: Tech833

Post Number: 857
Registered: 8-2002
Posted on Thursday, September 23, 2004 - 10:03 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Bob, you are not a bother. It is my pleasure.

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